Magnetic flow meters measure the velocity of conductive fluids passing through pipes by generating a magnetic field and measuring the resultant voltage. These flowmeters rely upon Faraday's Law in which the flow of a conductive fluid through a magnetic field causes a voltage signal which is sensed by electrodes and the sensed voltage is proportional to the fluid velocity.
Magnetic flowmeter assemblies are generally either insertion mag-meters or full bore mag-meters. Insertion mag-meters typically include a sensor body which is placed into a fluid flow and electrodes which are disposed at the distal end of the sensor body. The sensor can include conductive coils that generate a magnetic field which, in combination with the fluid flow creates an electromotive force (voltage), which is then sensed by the electrodes. Full bore mag-meters typically include a tubular body disposed inline along a fluid conduit, with conductive coils disposed on the tubular body that generates a magnetic field across the body and electrodes inserted into the walls of the body.
Although these flowmeters are generally effective, shortfalls exist. For example, these devices can suffer from temperature variations which affect the resistance of the conductive coils, thereby affecting the current flowing through the coils and potentially altering the magnetic field within the fluid flow path and the resultant measured voltage, assuming constant flow rate. Moreover, since the conductive coils can be paired, any deviation between the pair of coils potentially changes the symmetry of the magnetic field, also resulting in an altered magnetic field. These changes to the magnetic field can adversely impact the measurement accuracy of the flowmeter.
It should, therefore, be appreciated there remains a need for a magnetic flowmeter assembly that addresses these concerns. The present invention fulfills these needs and others.